Making of seamless steel tubes



Oct. 15, 1940. E. c. WRIGHT MAKING OF SEAILLESS STEEL TUBES Filed oct. 7. 1959 2m@ Km@ Patented Oce-15, 1940 UNITED sTATVEs. PATENT OFFICE" 2,218,458 v mmc oF sEAMLEss STEEL Tunas lnam c. wright, nemers.,- mignm :0N:-

tionai Tube Company, a corporation oi New Jersey Application-octane: 1, 1839, serial No. 298,467 vs claims. 1. zat-,156)

This invention 'is yconcerned witheconomically making 'seamless steel tubes in large quantities.

the primary object being to carry out the step of making the steel by `using a Bessemer converter instead of the more expensive'open hearth fur` io ring the steel is carried out infaBessemer converterwith its attendant economies intime and money. A subseq'uent step is to pour the molten steel produced by thev converter into a ladle and to pour molten pig iron "into, thisladle. By ,prop- 16 erly proportloning the amount of pig iron used to the quantity of steel in the ladle, vit is possible to deoxidize the steel to a degree of oxidation not exceeding nthat of steel made in a basic open hearth furnace, without materially increasing the 20 carbon content of the steel. i

Y Steel produced in a Bessemer converter contains large amounts of oxygen normally necessi- "tatingits being processed as either a rimming or a conventionally capped lsteel that, is not adapted for use in conjunction with thebillet piercing step in so far as the economical quantity production of seamless tubes is concerned. 'I'he steel cannot be produced satisfactorily asa killed steel because it contains so much oxygen l 80 that prior art methods of deoxidation are impractical. This discussion applies when the steel is not recarburized to a carbon content of more than .50%.

After this deoxidation with the pig iron step,`

the steel is completely killed and formed into solid ingots. Succeeding steps include rolling the solid ingots into billets, piercing these billets in a;

seamless tube piercing mill and processing the pierced billets into finished seamless steel tubes.,

40 'Ihese steps may be carried out in practically the v same manner as when the step of making the.

, steel is carried out by resorting toI a basic open hearth furnace or/an electric furnace. As a specific exampleof the invention, steel is made in two conventionally operated' 25 ton the oxygen in the steel and escaping, presumably, as C0 gas. This reaction is allowed to proceed to practical completion, at which time the carbon content of the molten steel in the ladle drops to approximately fromv .10% to .12% while the FeO 5 foutent of the steel is lowered to about .15% `or ess. l At this time ferrosilicon is added tothe molten steel to provide the finished steel with a silicon content of from, 15% to` .20%, along with suilo cient manganese toprovide the fiiushed steel `with a manganese content of from ..i0% toV l.%, as desired. Aluminum in the ratio of from 1 .to `2 pounds per ton of nfolten steel is ,subsequentlyv added to completely kill the steel. ,The steel can l5 be cast in molds withl hot tops, if desired.

It is 'to be particularly noted that the addition of from30 todo` pounds of molten pig iron per ton of molten steel that is highly oxidized by being `made in a Bessemer converter, results in 20 a steel that is at most no more oxidized than is equally low carbon steel made in a basic open hearth furnace, whereby this steel can be completely killed by the usel of ordinarily small amounts. of aluminum. 'Ihis killed steel is 25 adapted to be used in conjunction with the succeeding steps necessary to produce seamless steel tubes, namely, by being formed into solid ingots which are then rolled into suitable billets, the billets being pierced in a seamless tube piercing 3o mill and the resulting pierced billets being processed into finished seamless steel tubes. Furthermore, the steps can be carried out so as to Yeconomically producelarge quantities of the tubes. 35

The various steps disclosed herein are illustrated by the accompanying drawing. lin this drawing the various steps are identified by legends, it being-understood that conventional equipment may be used in carrying out these 4o steps.

1. In the art of making seamless steel tubes. the steps of making molten steel in a Bessemer converter, deoxidizing this molten steel by add- 4t l 2. In the art ofvmaking seamless steel tubes. thesteps of making molten steel ina Bessemer converter, pouring this molten steel in a ladle, pouring molten pig iron ln the ladle with the steel therein in the amount of about'trom 30 to 40 pounds of pig, iron per ton oi' steel, allowing reaction to proceed to substantial-completion between the carbon in the pig-iron and theoxygen in the steel, casting .the steel into ingot molds 1o) and producing solid-ingots, rolling the solid ingots into billets, piercingthese billets in a seamless tube piercing mill and processing the resulting pierced billets into nnished seamless steel tubes.,

3. In the art oi making seamless steel tubes, the steps of making molten steel in a Bessemer converter, pouring this molten steel in a ladle. pouring molten pig iron in the ladle with the steel therein in the amount o! about from 30 to 20 40 pounds of pig iron per ton oi.' steel. allowing reaction to proceed to substantial completion between the carbon in the pig iron and the oxygen in the steel, casting the steel into ingot molds and producing solid ingots, rolling the solid in- 25 gots into billets, piercing these billets in a seamless tube piercing mill and processing the resulting pierced billets intov linished seamless steel tubes, the pig iron functioning to deoxidlze the steel as it is made in the Bessemer converter to 30 a degree of oxidation not exceeding that ,of steel of comparable carbon content made in a basic open hearth'furnace and the steel being completely killed prior to its solidiilcation into ingots. 4.In the art oi' making seamless tubes. the

35 steps of making molten steel in a Bessemer converter, adding molten pig iron -to this steel in anV amount sumcient to deoxidize the steel al it is made inthe Bessemer converter to a degree oi oxidation not exceeding that of steel parable carbon content made in a basic open hearth furnace and insuiliclent to raise the csrbon content of said steel to more than .50 per- 6 cent. allowing the reaction between the carbo inthe pig. iron and the oxygen in the steel to proceed to substantial completion. casting the deoxidized steel into ingot molds and producing solid ingots, said steel being completely killed'10 prior to its solidiiication'into ingots. rolling the solid ingots into billets, piercing these billets in a seamless tube piercing mill and processing the resulting pierced billets into finished seamless tubes.

5. In the art oi making seamlesstubes, the steps oi mahng molten steel in a er oonverter, adding molten pig iron to this steel in an amount of at least 30 lbs. ormore per ton oi steel. allowing the reaction between the carbon in the pig iron and the oxygen in the steel to proceed to substantial completion. casting the deoxidlzed steel into ingot molds and producing solid ingots. said steel being completely killed prier te mi llamemos into more. renin; the

solid ingots into billets. piercing these billets in a seamless tube piercing mill and processing the resulting pierced billets intok finished seamless tubes, the amount of pig iron added being sumelent to deoxldize the steel as i: is mede in the Bessemer converter to a degree oi oxidation-not exceeding that o! steel o! comparable carbon contentmadeinabasicopenhearthfurnaccand.

lnsuilicient to raise the carbon content of the steel above .50 percent.

AEDwm c. WRIGHT. 

